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Douglas D. Buhler - One of the best experts on this subject based on the ideXlab platform.
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Herbicide Clomazone does not inhibit in vitro geranylgeranyl synthesis from mevalonate.
Plant physiology, 1992Co-Authors: Monte R. Weimer, Nelson E. Balke, Douglas D. BuhlerAbstract:Clomazone reduced the chlorophyll and carotenoid contents of spinach (Spinacia oleracea L.), barley (Hordeum vulgare L.), velvetleaf (Abutilon theophrasti Medik.), and soybean (Glycine max L. Merr.) seedlings. The order of species sensitivity was velvetleaf > spinach > barley > soybean. Clomazone (100 micromolar) did not affect the in vitro activities of spinach isopentenyl pyrophosphate isomerase or prenyl transferase. Clomazone also did not affect the synthesis of isopentenyl pyrophosphate from mevalonic acid. Thus, Clomazone had no direct in vitro effect on the synthesis of geranylgeranyl pyrophosphate from mevalonic acid. Greening seedlings of both soybean and velvetleaf metabolized Clomazone. No qualitative differences in the metabolites were detected between soybean and velvetleaf. Thus, differential metabolism of Clomazone to a toxic chemical that inhibits terpenoid synthesis is unlikely. Clomazone has either a mode of action not yet identified or a metabolite that is selective in that it is much more active in sensitive than tolerant species.
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Absorption and metabolism of Clomazone by suspension-cultured cells of soybean and velvetleaf
Pesticide Biochemistry and Physiology, 1992Co-Authors: Monte R. Weimer, Nelson E. Balke, Douglas D. BuhlerAbstract:Abstract Clomazone uptake and metabolism were compared in soybean and velvetleaf suspension cultured cells utilizing either [14C]methylene-Clomazone or [14C]carbonyl-Clomazone. Velvetleaf cells absorbed more Clomazone than soybean did. Cells of both species accumulated more metabolites when treated with [14C]methylene-Clomazone than when treated with [14C]carbonyl-Clomazone. Higher amounts of [14C]metabolites were present in the media of cells treated with [14C]carbonylClomazone than [14C]methylene-Clomazone. Differences in uptake were due to cellular retention of the benzyl moiety and efflux of the heterocyclic moiety after cleavage of Clomazone. All metabolites produced in soybean and velvetleaf cells were more polar than Clomazone. No qualitative differences in the metabolites produced by soybean and velvetleaf were identified. Both soybean and velvetleaf oxidatively cleaved the Clomazone molecule and subsequently conjugated the benzyl moiety with glucose. One of the aglycones was identified as 2-chlorobenzylalcohol. Oxidative cleavage of Clomazone was a major metabolic reaction occurring in both the tolerant (soybean) and susceptible (velvetleaf) species.
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Clomazone selectivity absence of differential uptake translocation or detoxication
Weed Science, 1991Co-Authors: Monte R. Weimer, Douglas D. Buhler, Nelson E. BalkeAbstract:Concentrations of Clomazone in nutrient solution causing 50% reduction in shoot fresh weights were 325 and 2 μM for soybean and velvetleaf, respectively. Root uptake of14C–Clomazone from nutrient solution and translocation to shoots were similar for the two species. Soybean and velvetleaf contained similar amounts of14C per plant; however, because velvetleaf had lower tissue weights, concentration of14C was higher in velvetleaf. Clomazone did not accumulate in roots but was rapidly translocated to shoots of both species. No more than 30% of absorbed Clomazone remained in roots at any time in the experiment. Soybean and velvetleaf leaves contained 4.2 and 1.7 nmol Clomazone g−1fresh weight, respectively, and 3.7 and 6.1 nmol Clomazone metabolites g−1fresh weight, respectively. Thus, velvetleaf metabolized Clomazone more rapidly than soybean did. Treatment of Clomazone metabolites with β-glucosidase demonstrated that metabolism occurred by oxidative cleavage and conjugation of the benzyl moiety in both plant species. One aglycone cochromatographed with 2–chlorobenzylalcohol. The results suggest that reduced absorption or translocation or increased detoxication of Clomazone by soybean seedlings is probably not responsible for their tolerance to this herbicide.
Monte R. Weimer - One of the best experts on this subject based on the ideXlab platform.
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Herbicide Clomazone does not inhibit in vitro geranylgeranyl synthesis from mevalonate.
Plant physiology, 1992Co-Authors: Monte R. Weimer, Nelson E. Balke, Douglas D. BuhlerAbstract:Clomazone reduced the chlorophyll and carotenoid contents of spinach (Spinacia oleracea L.), barley (Hordeum vulgare L.), velvetleaf (Abutilon theophrasti Medik.), and soybean (Glycine max L. Merr.) seedlings. The order of species sensitivity was velvetleaf > spinach > barley > soybean. Clomazone (100 micromolar) did not affect the in vitro activities of spinach isopentenyl pyrophosphate isomerase or prenyl transferase. Clomazone also did not affect the synthesis of isopentenyl pyrophosphate from mevalonic acid. Thus, Clomazone had no direct in vitro effect on the synthesis of geranylgeranyl pyrophosphate from mevalonic acid. Greening seedlings of both soybean and velvetleaf metabolized Clomazone. No qualitative differences in the metabolites were detected between soybean and velvetleaf. Thus, differential metabolism of Clomazone to a toxic chemical that inhibits terpenoid synthesis is unlikely. Clomazone has either a mode of action not yet identified or a metabolite that is selective in that it is much more active in sensitive than tolerant species.
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Absorption and metabolism of Clomazone by suspension-cultured cells of soybean and velvetleaf
Pesticide Biochemistry and Physiology, 1992Co-Authors: Monte R. Weimer, Nelson E. Balke, Douglas D. BuhlerAbstract:Abstract Clomazone uptake and metabolism were compared in soybean and velvetleaf suspension cultured cells utilizing either [14C]methylene-Clomazone or [14C]carbonyl-Clomazone. Velvetleaf cells absorbed more Clomazone than soybean did. Cells of both species accumulated more metabolites when treated with [14C]methylene-Clomazone than when treated with [14C]carbonyl-Clomazone. Higher amounts of [14C]metabolites were present in the media of cells treated with [14C]carbonylClomazone than [14C]methylene-Clomazone. Differences in uptake were due to cellular retention of the benzyl moiety and efflux of the heterocyclic moiety after cleavage of Clomazone. All metabolites produced in soybean and velvetleaf cells were more polar than Clomazone. No qualitative differences in the metabolites produced by soybean and velvetleaf were identified. Both soybean and velvetleaf oxidatively cleaved the Clomazone molecule and subsequently conjugated the benzyl moiety with glucose. One of the aglycones was identified as 2-chlorobenzylalcohol. Oxidative cleavage of Clomazone was a major metabolic reaction occurring in both the tolerant (soybean) and susceptible (velvetleaf) species.
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Clomazone selectivity absence of differential uptake translocation or detoxication
Weed Science, 1991Co-Authors: Monte R. Weimer, Douglas D. Buhler, Nelson E. BalkeAbstract:Concentrations of Clomazone in nutrient solution causing 50% reduction in shoot fresh weights were 325 and 2 μM for soybean and velvetleaf, respectively. Root uptake of14C–Clomazone from nutrient solution and translocation to shoots were similar for the two species. Soybean and velvetleaf contained similar amounts of14C per plant; however, because velvetleaf had lower tissue weights, concentration of14C was higher in velvetleaf. Clomazone did not accumulate in roots but was rapidly translocated to shoots of both species. No more than 30% of absorbed Clomazone remained in roots at any time in the experiment. Soybean and velvetleaf leaves contained 4.2 and 1.7 nmol Clomazone g−1fresh weight, respectively, and 3.7 and 6.1 nmol Clomazone metabolites g−1fresh weight, respectively. Thus, velvetleaf metabolized Clomazone more rapidly than soybean did. Treatment of Clomazone metabolites with β-glucosidase demonstrated that metabolism occurred by oxidative cleavage and conjugation of the benzyl moiety in both plant species. One aglycone cochromatographed with 2–chlorobenzylalcohol. The results suggest that reduced absorption or translocation or increased detoxication of Clomazone by soybean seedlings is probably not responsible for their tolerance to this herbicide.
Krishna N. Reddy - One of the best experts on this subject based on the ideXlab platform.
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Clomazone volatilization under varying environmental conditions
Chemosphere, 1996Co-Authors: Martin A. Locke, Reid J. Smeda, Kevin D. Howard, Krishna N. ReddyAbstract:Abstract Velvetleaf ( Abutilon theophrasti Medik.) was used as a bioindicator to examine factors (temperature, soil moisture, soil incorporation) which might influence Clomazone {2-[(2-chlorophenyl)methyl] -4,4-dimethyl-3-isoxazolidinone} volatilization. Young plants were periodically exposed to atmosphere inside boxes containing Clomazone-treated soil. Exposed plants were returned to the greenhouse for 5 to 7 d, and new leaves were assayed for chlorophyll. Maximum chlorophyll inhibition occurred in velvetleaf exposed during the first 2 wk after Clomazone application. Reductions in degree of bleaching were first observed in plants exposed in the treatments with lower soil moisture (2% moisture at 19 days after Clomazone treatment, DAT; 9% at 42 DAT). The least amount of Clomazone was measured in soils incubated in the 35 °C treatment, indicating elevated temperatures enhanced volatilization, and may have contributed to the increased chlorophyll content observed observed earlier than other temperatures. The effect of herbicide incorporation was not conclusive.
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Printed in Great Britain 0045-6535/96 $15.00+0.00 Clomazone VOLATILIZATION UNDER VARYING ENVIRONMENTAL CONDITIONS
1996Co-Authors: Kevin D. Howard, Krishna N. ReddyAbstract:Velvetleaf (Abutilon theophrasti Medik.) was used as a bioindicator to examine factors (temperature, soil moisture, soil incorporation) which might influence Clomazone {2-[(2-chlorophenyl)methyl]-4,4-dimethyl-3-isoxazolidinone} volatilization. Young plants were periodically exposed to atmosphere inside boxes containing Clomazone-treated soil. Exposed plants were returned to the greenhouse for 5 to 7 d, and new leaves were assayed for chlorophyll. Maximum chlorophyll inhibition occurred in velvetleaf exposed during the first 2 wk after Clomazone application. Reductions in degree of bleaching were first observed in plants exposed in the treatments with lower soil moisture (2 % moisture at 19 days after Clomazone treatment, DAT; 9 % at 42 DAT). The least amount of Clomazone was measured in soils incubated in the 35 °C treatment, indicating elevated temperatures enhanced volatilization, and may have contributed to the increased chlorophyll content observed observed earlier than other temperatures. The effect of herbicide incorporation was not conclusive. Published by Elsevier Science Lt
Nelson E. Balke - One of the best experts on this subject based on the ideXlab platform.
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Herbicide Clomazone does not inhibit in vitro geranylgeranyl synthesis from mevalonate.
Plant physiology, 1992Co-Authors: Monte R. Weimer, Nelson E. Balke, Douglas D. BuhlerAbstract:Clomazone reduced the chlorophyll and carotenoid contents of spinach (Spinacia oleracea L.), barley (Hordeum vulgare L.), velvetleaf (Abutilon theophrasti Medik.), and soybean (Glycine max L. Merr.) seedlings. The order of species sensitivity was velvetleaf > spinach > barley > soybean. Clomazone (100 micromolar) did not affect the in vitro activities of spinach isopentenyl pyrophosphate isomerase or prenyl transferase. Clomazone also did not affect the synthesis of isopentenyl pyrophosphate from mevalonic acid. Thus, Clomazone had no direct in vitro effect on the synthesis of geranylgeranyl pyrophosphate from mevalonic acid. Greening seedlings of both soybean and velvetleaf metabolized Clomazone. No qualitative differences in the metabolites were detected between soybean and velvetleaf. Thus, differential metabolism of Clomazone to a toxic chemical that inhibits terpenoid synthesis is unlikely. Clomazone has either a mode of action not yet identified or a metabolite that is selective in that it is much more active in sensitive than tolerant species.
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Absorption and metabolism of Clomazone by suspension-cultured cells of soybean and velvetleaf
Pesticide Biochemistry and Physiology, 1992Co-Authors: Monte R. Weimer, Nelson E. Balke, Douglas D. BuhlerAbstract:Abstract Clomazone uptake and metabolism were compared in soybean and velvetleaf suspension cultured cells utilizing either [14C]methylene-Clomazone or [14C]carbonyl-Clomazone. Velvetleaf cells absorbed more Clomazone than soybean did. Cells of both species accumulated more metabolites when treated with [14C]methylene-Clomazone than when treated with [14C]carbonyl-Clomazone. Higher amounts of [14C]metabolites were present in the media of cells treated with [14C]carbonylClomazone than [14C]methylene-Clomazone. Differences in uptake were due to cellular retention of the benzyl moiety and efflux of the heterocyclic moiety after cleavage of Clomazone. All metabolites produced in soybean and velvetleaf cells were more polar than Clomazone. No qualitative differences in the metabolites produced by soybean and velvetleaf were identified. Both soybean and velvetleaf oxidatively cleaved the Clomazone molecule and subsequently conjugated the benzyl moiety with glucose. One of the aglycones was identified as 2-chlorobenzylalcohol. Oxidative cleavage of Clomazone was a major metabolic reaction occurring in both the tolerant (soybean) and susceptible (velvetleaf) species.
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Clomazone selectivity absence of differential uptake translocation or detoxication
Weed Science, 1991Co-Authors: Monte R. Weimer, Douglas D. Buhler, Nelson E. BalkeAbstract:Concentrations of Clomazone in nutrient solution causing 50% reduction in shoot fresh weights were 325 and 2 μM for soybean and velvetleaf, respectively. Root uptake of14C–Clomazone from nutrient solution and translocation to shoots were similar for the two species. Soybean and velvetleaf contained similar amounts of14C per plant; however, because velvetleaf had lower tissue weights, concentration of14C was higher in velvetleaf. Clomazone did not accumulate in roots but was rapidly translocated to shoots of both species. No more than 30% of absorbed Clomazone remained in roots at any time in the experiment. Soybean and velvetleaf leaves contained 4.2 and 1.7 nmol Clomazone g−1fresh weight, respectively, and 3.7 and 6.1 nmol Clomazone metabolites g−1fresh weight, respectively. Thus, velvetleaf metabolized Clomazone more rapidly than soybean did. Treatment of Clomazone metabolites with β-glucosidase demonstrated that metabolism occurred by oxidative cleavage and conjugation of the benzyl moiety in both plant species. One aglycone cochromatographed with 2–chlorobenzylalcohol. The results suggest that reduced absorption or translocation or increased detoxication of Clomazone by soybean seedlings is probably not responsible for their tolerance to this herbicide.
Patrick L. Tomco - One of the best experts on this subject based on the ideXlab platform.
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Biodegradation of Clomazone in a California rice field soil: carbon allocation and community effects.
Journal of agricultural and food chemistry, 2013Co-Authors: Patrick L. Tomco, William E. Holmes, Ronald S. TjeerdemaAbstract:Degradation pathways for the herbicide Clomazone in a California rice field soil were characterized via pulse-labeling of anaerobic (flooded) and aerobic (moist) soil microcosms. Clomazone-derived ...
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Photolytic versus microbial degradation of Clomazone in a flooded California rice field soil.
Pest management science, 2012Co-Authors: Patrick L. Tomco, Ronald S. TjeerdemaAbstract:BACKGROUND: Clomazone is a popular herbicide used on California rice fields and exhibits rapid anaerobic microbial degradation (t1/2 = 7.9 days). To test the potential of direct and indirect photolytic degradation as a cofactor in the overall degradation rate, sacrificial time-series microcosms were amended with water, non-sterilized soil + water and sterilized soil + water. Clomazone was added to each microcosm, which was then exposed to natural and artificial sunlight over 35 days. Water and acetonitrile extracts were analyzed for Clomazone and metabolites via LC/MS/MS. RESULTS: The calculated pseudo-first-order degradation rate constants (k) were kwater = 0–0.005 ± 0.003 day−1, ksterile = 0–0.005 ± 0.003 day−1 and knon−sterile = 0.010 ± 0.002–0.044 ± 0.007 day−1, depending on light type. The formation of ring-open Clomazone, a microbial metabolite, correlated with Clomazone degradation. Trace amounts of 5-hydroxyClomazone (m/z = 256 125), aromatic hydroxyClomazone (m/z = 256 141) and an unknown product (m/z = 268 125) were observed. CONCLUSIONS: The photolytic degradation rate depends on both light type and the quality of the chromophores that induce indirect photolysis. Microbial degradation was found to be sensitive to temperature fluctuations. Overall, microbes are shown to be more detrimental to the environmental fate of Clomazone than photolysis. Copyright © 2012 Society of Chemical Industry
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Microbial degradation of Clomazone under simulated California rice field conditions.
Journal of agricultural and food chemistry, 2010Co-Authors: Patrick L. Tomco, Wei Zou, Dirk M. Holstege, Ronald S. TjeerdemaAbstract:Clomazone (trade names Cerano and Command) is a popular herbicide used on California rice fields to control aquatic weeds. Its physicochemical characteristics indicate that it will persist primarily in the water column, where microbial degradation may drive its environmental fate. The objectives were to determine microbial degradation rates and compare the metabolic products under aerobic and anaerobic conditions similar to those in California rice fields during the summer. Time-series samples were extracted and analyzed by LC/MS/MS. Metabolic profiling revealed the following Clomazone-derived transitions: m/z 240 --> 125 (Clomazone), m/z 242 --> 125 (ring-open Clomazone), m/z 256 --> 125 (5-hydroxyClomazone), m/z 256 --> 141 (aromatic hydroxyClomazone), m/z 268 --> 125 (unknown metabolite), and m/z 272 --> 141 (4'5-dihydroxyClomazone). Results indicate an anaerobic half-life of 7.9 days, with ring-open Clomazone reaching 67.4% of application at 38 days. Aerobically, Clomazone degraded more slowly (t(1/2) = 47.3 days), forming mostly soil-bound residues. Thus, under summer conditions, Clomazone is likely to dissipate rapidly from fields via anaerobic degradation.